The present invention generally relates to a coupling for connecting a deformable hose with a pipe, tube or hose. It also relates to a method for making such a coupling. In particular, the invention may be used in automotive carbon dioxide air conditioning refrigerant systems for connecting a metal tube with a polymer hose.
Due to automotive design considerations, it has been common for an automobile""s air conditioning system to contain couplings which connect a metal pipe to a polymer deformable hose. Recently developed automotive refrigerant systems utilizing carbon dioxide as a refrigerant require new coupling design considerations to handle the higher system pressures and relatively small molecular size of the carbon dioxide molecule. The higher system pressures expose traditional coupling designs to sudden destructive decompression when system pressure is suddenly lost, causing damage to the sealing members. Additionally, the relatively small molecular size of carbon dioxide results in increased permeability of the gas using traditional coupling designs.
Briefly stated, in accordance with one aspect of the present invention, a coupling is provided that includes a connector member comprising a stem section and a receiving section connected to the stem section. The connector member also defines an internal passage. The stem section comprises an exterior surface and at least one circumferential groove formed therein, defining a volume. The coupling also defines at least one seal member disposed within the at least one circumferential groove. The seal member has an exterior surface and has a volume that is less than the volume of the circumferential groove. The coupling also comprises a deformable hose fitted over the stem section and covering the at least one circumferential groove. The coupling also comprises a collar disposed over the deformable hose. The collar comprises at least one radially extending protrusion engaging the hose and bringing the hose into engagement with the exterior surface of the seal member wherein the seal member and hose fill substantially 100% of the volume of the circumferential groove.
In accordance with another aspect of the invention, a method of assembling a coupling is provided. The steps of assembly first provide for a connector member having an internal passageway and at least one circumferential groove. At least one seal member is then disposed into at least one circumferential groove wherein the seal member has a volume less than the circumferential groove. A collar is then disposed over the connector member. The connector member is then inserted into an end of a deformable hose so that the deformable hose covers at least one circumferential groove containing a seal member. Radial protrusions are then formed into the collar. The protrusions force a portion of the deformable hose into at least one circumferential groove containing a seal member and engage the seal member such that the deformable hose and seal member occupy substantially 100% of the volume of at least one circumferential groove.
In accordance with yet another aspect of the invention, a method of using the coupling is provided. A coupling is first provided wherein the coupling comprises a connector member, a deformable hose fitted over the connector member, and a collar disposed over the connector member. The collar comprises a radial protrusion which engages the deformable hose which, in turn, engages a seal member disposed within at least one circumferential groove in the connector member. The deformable hose and seal member fill substantially 100% of the volume of the circumferential groove. In the second step of using the coupling, the hose and coupling are pressurized.
The present invention provides significant advantages over existing coupling designs. The invention, as described further below, addresses sudden destructive decompression by mechanically restricting expansion of the seal members in case of system depressurization. This mechanical restriction prevents damage to the seal members, allowing for the system to be pressurized again without the need for replacing the seal members. A further advantage of the present invention is that it presents an efficient simplified locking means to provide easier and more inexpensive manufacture and assembly. The invention also provides better sealing properties to limit permeation of the relatively small carbon dioxide molecule.
Advantages of the present invention will become readily apparent to those skilled in the art from the following description of the preferred embodiments of the invention which have been shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.